Predictive value and clinical utility of centrally assessed ER, PgR, and Ki-67 to select adjuvant endocrine therapy for premenopausal women with hormone receptor-positive, HER2-negative early breast cancer: TEXT and SOFT trials

Meredith M. Regan, Olivia Pagani, Prudence A. Francis, Gini F. Fleming, Barbara A. Walley, Roswitha Kammler, Patrizia Dell'Orto, Leila Russo, János Szőke, Franco Doimi, Laura Villani, Stefano Pizzolitto (+11 others)
2015 Breast Cancer Research and Treatment  
The SOFT and TEXT randomized phase III trials investigated adjuvant endocrine therapies for premenopausal women with hormone receptor-positive (HR+) early breast cancer. We investigated the prognostic and predictive value of centrally assessed levels of estrogen receptor (ER), progesterone receptor (PgR), and Ki-67 expression in women with HER2-negative disease. Of 5707 women enrolled, 4115 with HER2-negative (HR+/HER2-) disease had ER, PgR, and Ki-67 centrally assessed by immunohistochemistry.
more » ... Breast cancer-free interval (BCFI) was defined from randomization to first invasive local, regional, or distant recurrence or contralateral breast cancer. The prognostic and predictive values of ER, PgR and Ki-67 expression levels were assessed using Cox modeling and STEPP methodology. In this HR+/HER2-population, the median ER, PgR, and Ki-67 expressions were 95, 90, and 18 % immunostained cells. As most patients had strongly ER-positive tumors, the predictive value of ER levels could not be investigated. Lower PgR and higher Ki-67 expression were associated with reduced BCFI. There was no consistent evidence of heterogeneity of the relative treatment effects according to PgR or Ki-67 expression levels, though there was a greater 5-year absolute benefit of exemestane + ovarian function suppression (OFS) versus tamoxifen with or without OFS at lower levels of PgR and higher levels of Ki-67. Women with poor prognostic features of low PgR and/or high Ki-67 have greater absolute benefit from exemestane + OFS versus tamoxifen + OFS or tamoxifen alone, but individually PgR and Ki-67 are of limited predictive value for selecting adjuvant endocrine therapy for premenopausal women with HR+/HER2-early breast cancer.
doi:10.1007/s10549-015-3612-z pmid:26493064 pmcid:PMC4749471 fatcat:f6eve7kgbrfxtbc4rf2rzn7idq